The thermoelectric power generating device has the characteristics of the conversion between heat and electricity, and is a solid state structure without using any movement components. Normally, the thermoelectric power generating device is formed by P type and N type thermoelectric materials connected in serial, a conductive metal layer, a solder, and an upper substrate and a lower substrate which are electrically isolated from each other. When the upper substrate and the lower substrate of the thermoelectric power generating device have different temperatures, that is, when the substrate module has temperature difference, the thermoelectric power generating device generates a DC current. The direction of the direct current is related to the disposition order of the P/N thermoelectric materials and the relative cold/hot positions thereof.
To increase the thermoelectric conversion efficiency of the thermoelectric power generating device, the industries are engaged in improving the characteristics of the thermoelectric material.